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GATE 2020 IN – Question 45

Signals and Systems · Signals and linear time-invariant systems: Periodic, aperiodic and impulse signals, continuous-time and discrete-time systems, transfer function, LTI systems, impulse response, frequency response, pulse transfer function, convolution, correlation · 2 marks · Numerical answer

Let $g[n]=1$ for n = 0 and zero otherwise, and $h[n]=1$ for n = 0,3,6,9,… and zero otherwise. If $y[n]=h[n]\otimes g[n]$ with convolution denoted by ⊗, find y[2].

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Correct answer: 0 to 0

Explanation

The sequence g[n] is the unit impulse δ[n]. Convolution with the unit impulse leaves the other sequence unchanged: $h[n]*\delta[n]=h[n]$. Since 2 is not a nonnegative multiple of 3, h[2] = 0. Therefore y[2] = 0.

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